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Karon L Smith Michael D Steven Jeremy J Colls. ASGARD ( Artificial soil gassing and response detection) –background. An understanding is required of the risk of leakage from the storage sites or from the infrastructure used to transport the CO 2
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Karon L Smith Michael D Steven Jeremy J Colls
ASGARD (Artificial soil gassing and response detection) –background • An understanding is required of the risk of leakage from the storage sites or from the infrastructure used to transport the CO2 • Detection of leaks and knowledge of the effect of leaking CO2 on surface ecosystems is important. • Our approach is to inject controlled amounts of CO2 into soil • Test detection techniques using remote sensing or isotope analysis • Monitor changes in plant and soil conditions • Test sensitivity to soil and plant types and gassing rate
ASGARD –development of experimental site • The site was set up at the University of Nottingham’s Sutton Bonington campus • 34 plots each 2.5 x 2.5 m were marked out and prepared with 3 crops. • 8 were left as pasture • 8 plots were planted with barley • 8 plots were planted with linseed • 6 plots were left for additional experiments • 4 plots were marked out at a distance from the main site to act as remote controls
ASGARD –development of experimental site • CO2 gas was delivered at a depth of 60 cm to 4 plots in each crop from 200 l cryotanks via MDPE pipes • Gas delivery was controlled with solenoid operated mass flow controllers • Gas was delivered at a rate of 3 l hr-1 between 16th May and 26th September 2006
Gas concentration • Soil gas concentration was measured on a daily basis using permanently installed sampling tubes.
Gas distribution within plots • Barholes, 30 cm deep, were made at 50 cm intervals over the plot. CO2 measurements were taken using the GA2000 gas detector
Surface CO2 measurements • Draegar tubes were used to measure CO2 at the surface
CO2 flux measurements • CO2 flux was measured by BGS using a West systems fluxmeter Correlation of CO2 flux with soil CO2 concentration
Vegetation stress • Spectral measurements were taken at 50 cm intervals along a transect in each plot.
Effect of CO2 flow-rate • Four flow-rates were tested. • 3, 2, 1 and 0.5 l min-1 • In future experiments a flow rate of 2 l min-1 will be used to maximise spread of CO2 throughout the soil whilst minimising costs.
Conclusions • We have successfully developed the ASGARD facility and demonstrated: • Controlled release of CO2 into the soil • Demonstration of CO2 movement within, and flux out of the plots • Detection of plant stress effects through spectral monitoring and the ability to identify leaking CO2 at low soil concentrations • Successful use of isotopes in discriminating between geological and biogenic carbon for identification of leaking CO2 • We believe that characterisation of leaking CO2 hazards in the environment and validation of detection techniques will help to provide the basis for public confidence in CCS.
Acknowledgments We would like to thank UKCCSC and SRIF3 for funding this project We also thank Darren Hepworth, Maria Ortega and Marta Ortega for their help during the field season.